JPH05131602A - Laminated polyester film - Google Patents

Abstract

PURPOSE:To provide a laminated polyester film where a defect of the laminated polyester film obtained by laminating conventional different kinds of polyester, for example, ply separation or formation of curling or cupping is cancelled. CONSTITUTION:The title film is a laminated film obtained by laminating a film layer of polyester A and a film layer of polyester B which is different from the film layer of the polyester A and a layer constituted of a copolymer of the polyester A and polyester B is provided in the middle of both the film layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly to a biaxially oriented laminated polyester film useful as a base film for high density magnetic recording media.

[0002]

2. Description of the Related Art Polyester films typified by polyethylene terephthalate films have excellent mechanical properties, chemical properties, and thermal properties and are widely used. In particular, it is used in large quantities as a base film for magnetic recording media.

By the way, the polyester film is often required to have different properties on both surfaces, for example, one surface is required to be a smooth surface and the other surface is required to be a smooth surface. Further, further improvement of the surface characteristics of the polyester film is required.

As a means for improving the surface characteristics of polyester films, a method of laminating different polyester films is known, and further, JP-A-61-278022, JP-A-62-108053 and JP-A-63-120646 are known.
No. 63/853/1988, 63/872/1988
31, JP-A-63-197643, JP-A-63-2
Many proposals such as No. 12549 have been made.

[0005]

However, the following problems remain in these laminated films of different polyesters as problems to be solved. (1) When used as a base film for a magnetic recording tape or a flexible disk The layers of the base film (layers of different polyester layers) peel off when the tape is running or when repeated external force such as head touch of the flexible disk is applied. I have something to do. (2) Since different kinds of polyesters having different characteristics are laminated, for example, in a two-layer film, the film is likely to curl due to a bimetallic effect,
Cupping may occur when used as a magnetic tape. (3) When immersed in water, a solvent, or the like, problems such as peeling of the film of each layer from the boundary surface of the laminate may occur. (4) When used as a base film for magnetic recording, the magnetic layer is often applied to the base film and then subjected to calendering. However, heat and shear are applied to the base film in this step, and thus the layers may be separated. ..

[0006]

In order to achieve such an object, the present invention has the following constitution.

A laminated film comprising a polyester (A) film layer and a different polyester (B) film layer, wherein the polyester (A) and the polyester (B) have the same weight in the middle of the two film layers. A laminated polyester film having a layer formed of a united body.

In the present invention, as the polyester constituting the film, polyethylene-2,6-naphthalate, polyethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate and the like are preferably exemplified.

This polyethylene-2,6-naphthalate contains naphthalenedicarboxylic acid as a main acid component,
A small amount (preferably 20 mol% or less) of another dicarboxylic acid component may be copolymerized, and ethylene glycol is used as a main glycol component, but a small amount (preferably 20 mol% or less) of another glycol component is copolymerized. It is a polymer that may be polymerized. Examples of dicarboxylic acids other than naphthalenedicarboxylic acid include terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, aromatic dicarboxylic acids such as benzophenone dicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. Examples of glycol components other than ethylene glycol include 1,3-propanediol,
1,4-butanediol, 1,6-hexanediol,
Examples include neopentyl glycol, 1,4-cyclohexanedimethanol and p-xylylene glycol. In addition, stabilizers, colorants, lubricants,
It may be a mixture of additives such as a matting agent.

Such polyethylene-2,6-naphthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as catalysts can be optionally used.

The intrinsic viscosity of polyethylene-2,6-naphthalate is preferably in the range of 0.45 to 0.90.

The polyethylene terephthalate has terephthalic acid as a main acid component, but a small amount (preferably 20 mol% or less) of another dicarboxylic acid component may be copolymerized, and ethylene glycol is a main glycol component. However, a small amount (preferably 20 mol% or less)
It is a polymer which may be copolymerized with other glycol components. Examples of dicarboxylic acids other than terephthalic acid include aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, isophthalic acid, diphenyl sulfone dicarboxylic acid, and benzophenone dicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecane dicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. Examples of glycol components other than ethylene glycol include 1,3-propanediol and 1,4-
Examples thereof include butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol and the like. Further, the polymer may be mixed with additives such as a stabilizer, a colorant, a lubricant, and a matting agent.

Such polyethylene terephthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as catalysts can be optionally used.

The intrinsic viscosity of polyethylene terephthalate is preferably in the range of 0.45 to 0.90.

Although the poly-1,4-cyclohexylene dimethylene terephthalate has terephthalic acid as a main acid component, it may be copolymerized with a small amount (preferably 20 mol% or less) of another dicarboxylic acid component. Well again 1,4
-A polymer having cyclohexanedimethanol as a main glycol component, but may be copolymerized with a small amount (preferably 20 mol% or less) of another glycol component. Examples of dicarboxylic acids other than terephthalic acid include aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, isophthalic acid, diphenyl sulfone dicarboxylic acid, and benzophenone dicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecane dicarboxylic acid. And alicyclic dicarboxylic acids such as hexahydroterephthalic acid and 1,3-adamantanedicarboxylic acid. Examples of glycol components other than 1,4-cyclohexanedimethanol include ethylene glycol and 1,3-
Propanediol, 1,4-butanediol, 1,6-
Hexanediol, neopentyl glycol, p-xylylene glycol and the like can be mentioned. 1,
4-Cyclohexanedimethanol can be produced by, for example, a method of producing by catalytic reduction of dimethyl terephthalate or terephthalic acid, but there is no problem even if it is produced by any method. The ratio of the cis isomer to the trans isomer of 1,4-cyclohexanedimethanol is not particularly limited, but cis isomer / trans isomer = 4/6 to 0/10 is preferable.

Further, the polymer may be mixed with additives such as a stabilizer, a colorant, a lubricant and a matting agent.

Such poly-1,4-cyclohexylene dimethylene terephthalate is usually produced by a known method by a melt polymerization method. At this time, additives such as catalysts can be optionally used.

The intrinsic viscosity of poly-1,4-cyclohexylene dimethylene terephthalate is preferably in the range of 0.45 to 0.90.

The inert solid fine particles (lubricant) that can be contained in the polyester in the present invention are preferably (1) silicon dioxide (including hydrate, diatomaceous earth, silica sand, quartz, etc.); (2) Alumina; (3) SiO ₂
Silicates containing 30 wt% or more of components (for example, amorphous or crystalline clay minerals, aluminosilicates (including calcined products and hydrates), warm asbestos, zircon, fly ash, etc.); (4) Mg Oxides of Zn, Zr, and Ti;
(5) Ca and Ba sulfates; (6) Li, Na, and Ca phosphates (including monohydrogen salts and dihydrogen salts);
(7) Li, Na, and K benzoates; (8) Ca,
Terephthalates of Ba, Zn, and Mn; (9) Mg,
Ca, Ba, Zn, Cd, Pb, Sr, Mn, Fe, C
o and Ni titanates; (10) Ba and Pb chromates; (11) carbon (eg carbon black,
(Graphite etc.); (12) glass (eg glass powder,
Glass beads, etc.); (13) Ca and Mg carbonates;
(14) Fluorite and (15) ZnS are cited. More preferably, silicon dioxide, silicic anhydride, hydrous silicic acid, aluminum oxide, aluminum silicate (calcined product,
Hydrate, etc.), 1 lithium phosphate, 3 lithium phosphate,
Sodium phosphate, calcium phosphate, barium sulfate, titanium oxide, lithium benzoate, double salts of these compounds (including hydrates), glass powder, clay (including kaolin, bentonite, clay etc.), talc, diatomaceous earth, Examples include calcium carbonate. Particularly preferably, silicon dioxide,
Examples thereof include titanium oxide and calcium carbonate.

As the stabilizer, phosphorus compounds such as phosphoric acid, phosphorous acid and their esters can be preferably mentioned, and as the luster, titanium dioxide, silica, barium sulfate and the like can be preferably mentioned.

The laminated film of the present invention comprises at least two of the above-mentioned polyesters such as polyethylene-2,6-naphthalate and polyethylene terephthalate, polyethylene-2,6-naphthalate and poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene. A structure in which a film of polyester (A) and a film of polyester (B) are laminated using terephthalate and poly-1,4-cyclohexylene dimethylene terephthalate as polyester (A) and polyester (B) is used.
Then, a layer made of a copolymer of polyester (A) and polyester (B) is interposed between the two film layers. Such a copolymer is obtained by, for example, melt-mixing the polyester (A) and the polyester (B) and copolymerizing the polyester by a transesterification reaction and a redistribution reaction, and the constituent components of the polyester (A) and the polyester (B) are monomers. It can be produced by applying a conventionally known method such as a method of producing a copolyester by mixing in the state and changing the mixing ratio of each component.
Among these, the former method of melt-mixing the polyester (A) and the polyester (B) and copolymerizing them is simple and preferable.

The laminated film in the present invention is formed by laminating different kinds of polyester film layers, and the number of laminated layers may be two or more. That is, for example, polyethylene terephthalate and polyethylene-2,6
It may be two layers of naphthalate or polyethylene terephthalate as a core layer and poly-1,4-cyclohexylene dimethylene terephthalate laminated on both outer surfaces to form three layers. The point is to interpose a layer of a copolymer of these polyesters between these different polyesters, that is, between the polyester (A) and the polyester (B).

Polyester (A) and polyester (B)
The method of interposing the layer of the polyester copolymer between these layers is not particularly limited, but it is preferable to interpose the layer by a coextrusion method. That is, the dry pellets of polyester (A) and polyester (B) are prepared, and the pellets of both polyesters are mixed in a desired ratio and melt-mixed at a temperature for a predetermined time in a melt extruder to obtain pellets copolymerized. prepare. These three types of polyester pellets are fed to respective extruders and melted so that the copolymer layer comes from the three-layer coextrusion die to the intermediate layer between the polyester (A) layer and the polyester (B) layer. It is good to extrude into.

The extruding method is carried out by joining in a polymer pipe on the way of extruding, or by joining these polymers in an extruding die consisting of three layers in the thickness direction to form a single sheet on a casting drum. Extrude and cool.

The thickness of the layer of the copolyester interposed between the polyesters (A) and (B) is preferably 0.03 μm to 1.0 μm in the final product (biaxially oriented film). When the thickness is 1.0 μm or more, the mechanical properties originally possessed by the polyesters (A) and (B) are impaired, which is not preferable. Further, when the thickness of the copolyester layer is 0.03 μm or less, the effect of interposing the copolyester layer is almost lost, which is not preferable.

The composition of the copolyester is 60: 4 as the ratio of the polyester (A) and the polyester (B).
It is preferable to take 0 to 40:60. For example, polyester (A) is polyethylene-2,6-naphthalate (P
EN-2,6), when the polyester (B) is polyethylene terephthalate (PET), PET and PEN-
PET / PEN-2,6 = 60 as the ratio of 2,6 components
It is preferably in the range of / 40 to 40/60. If the ratio is out of this range, the function of strongly adhering the interface between PEN-2, 6 and PET even if these copolymers are interposed is not preferable.

Since the laminated film thus obtained is in an unstretched state, it is further subjected to stretch orientation and heat setting treatment.
The stretching orientation treatment may be either sequential biaxial stretching or simultaneous biaxial stretching, but the former is more preferable. The stretching method may be a known method, for example, longitudinal stretching can be performed while heating between two rolls having different peripheral speeds, and transverse stretching can be performed by gripping both ends of the film with clips and heating the clip row. Stretching can be performed by increasing the row spacing. As the stretching method, for example, a vertical-horizontal two-stage stretching method and a vertical-horizontal-vertical-horizontal four-stage stretching method can be applied.

[0028]

EXAMPLES The present invention will be further described below with reference to examples.

[0029]

Example 1, Comparative Example 1 Polyethylene terephthalate (PET: Polyester B) having an intrinsic viscosity of 0.60 dl / g (measured at 25 ° C. using orthochlorophenol as a solvent) containing substantially no lubricant, and Polyethylene-2 having an intrinsic viscosity of 0.58 dl / g, containing 0.3% by weight of silica particles having an average particle size of 0.1 μm and 0.020% by weight of calcium carbonate particles having an average particle size of 0.6 μm.
6-Naphthalate (PEN: Polyester A) was prepared. Each of these polymers was dried at 170 ° C. and then melted at 310 ° C. in a separate melt extruder. on the other hand,
These dry polymers were mixed in a weight ratio of 1: 1 and another 1
They were melt mixed by one melt extruder and held at 310 ° C. for 10 minutes (PEN-PET copolymer). These polymers were supplied from a polymer pipe and extruded from an extrusion die having a 5-layer structure. That is, PEN / PEN-PET copolymer / PET / PET-PEN copolymer / PEN
Was extruded so as to have a five-layer structure, combined and laminated in a die, and extruded from a die slit onto a cooled casting drum to be cooled to obtain an unstretched film.

This unstretched film was stretched in the longitudinal and transverse directions by 3.6.
Sequentially stretched by 3.6 times and heat set at 215 ° C., 75 μ
A laminated film having a thickness of m was obtained. At this time, the extrusion amount of the polymer was adjusted so that the thickness of each layer of the 5-layer structure was 10 / 1.0 / 53 / 1.0 / 10. (Example 1)

On the other hand, without interposing the copolymer of polyesters (A) and (B) between the polyesters (A) and (B),
PEN / PET / PEN was extruded from an extrusion die having a three-layer structure to prepare a biaxially stretched film having a thickness of 75 μm in the same manner as above. The thickness of each layer of this product is PEN / PET /
It was adjusted so that PEN = 10/55/10. (Comparative Example 1) The biaxially oriented laminated film thus obtained was cut into a 10 cm opening, immersed in water at room temperature for 1 hour, and then taken out for a peel test.

In the peel test, the cut edge of the film was squeezed with a finger to examine whether or not the film was separated into three pieces.

The film of Example 1 was not peeled at all, but the film of Comparative Example 1 was peeled into three thin films. Further, when notches were put in these films and pulled by hand in the front-rear direction, the films of Example 1 were torn in a substantially straight line in the notch direction.
It can be seen that the film of Comparative Example 1 is bent in the tearing direction or causes delamination of the film at the interface of lamination, and the polyester (A) and (B) layers do not have good adhesion at the interface. only.

[0034]

Example 2, Comparative Example 2 Polyethylene having an intrinsic viscosity of 0.62, containing 0.15% by weight of silica particles having an average particle size of 0.1 μm and 0.16% by weight of calcium carbonate particles having an average particle size of 0.6 μm. -2,6-Naphthalate (PEN) as well as polyethylene terephthalate (PET) with an intrinsic viscosity of 0.62, which is substantially free of lubricant, were melted at 310 ° C in separate melt extruders. In another melt extruder, PEN-having substantially the same lubricant and the same intrinsic viscosity as above
2,6 and PET are PET / PEN-2,6 = 55/4
5 (weight ratio) melted and kept at 310 ° C. for 10 minutes (PE
T-PEN copolymer). These molten polymers were extruded in a three-layer structure, combined in a die, extruded on a casting drum and cooled to obtain an unstretched film of PET / PET-PEN copolymer / PEN.

This unstretched film was stretched 4.85 times in the machine direction at a temperature of 120 ° C. between two rolls having a speed difference, and was further stretched in the transverse direction by a tenter at 145 ° C. and 5.1.
The film was stretched 5 times and then heat-treated at 215 ° C. for 10 seconds.
In this way, a 6 μm thick biaxially oriented polyester laminated film (thickness structure: PEN / PET-PEN copolymer / PET = 5 / 0.2 / 0.8) was wound. (Example 2)

A 6 μm biaxially oriented polyester laminated film (thickness structure: PEN / PET = 5.2 /) was prepared in exactly the same manner as in Example 2 except that no PET-PEN copolymer layer was interposed between the three-layer film. 0.8) was wound up.
(Comparative example 2)

On the other hand, the composition shown below was put in a ball mill, kneaded and dispersed for 16 hours, and then 5 parts by weight of an isocyanate compound (Desmodur L manufactured by Bayer) was added,
High-speed shear dispersion was carried out for 1 hour to obtain a magnetic paint. Composition of magnetic paints Needle-like Fe particles 100 parts by weight Vinyl chloride-vinyl acetate copolymer 15 parts by weight (Eslek 7A manufactured by Sekisui Chemical Co., Ltd.) Thermoplastic polyurethane resin 5 parts by weight Chromium oxide 5 parts by weight Carbon black 5 parts by weight Lecithin 2 parts by weight Parts Fatty acid ester 1 part by weight Toluene 50 parts by weight Methyl ethyl ketone 50 parts by weight Cyclohexanone 50 parts by weight This magnetic paint was applied to one side of the above-mentioned laminated film on the polyethylene terephthalate side so that the application thickness was 3 μm, and then 2500 Gauss DC magnetic field was applied. Orientation treatment was carried out in the inside, and after heating and drying at 100 ° C., super calendering treatment (linear pressure 200 kg / cm, temperature 80 ° C.) was carried out and the product was wound up. The wound roll was left for 3 days in the open at 55 ° C.

The electromagnetic conversion characteristics and running durability of the tape obtained from the film of Example 2 were good. However, the tape obtained from the film of Comparative Example 2 had poor running durability. That is, when the tape was repeatedly run 200 times on the tape deck, peeling occurred between the base film layers at the end surface of the tape.

[0039]

According to the present invention, the following effects can be obtained. 1. It is possible to prevent the occurrence of curling and cupping that often occur in a laminated biaxially oriented polyester film of different polymers. 2. It is possible to provide a base film that is extremely resistant to delamination and delamination between layers even when a force such as repeated bending is applied. 3. For example, when used as a flexible disk, the head touch is improved due to the flexible layer of the base film.

Front Page Continuation (72) Inventor Hisano Hamano 3-37-19 Koyama, Sagamihara City, Kanagawa Teijin Limited Sagamihara Research Center

Claims (4)

[Claims] 1. A laminated film in which a film layer of polyester (A) and a film layer of polyester (B) different from this are laminated, and a polyester (A) and a polyester (B) are provided in the middle of both film layers. A laminated polyester film provided with a layer made of a polymer. 2. The polyester (A) is polyethylene-2.
The laminated polyester film according to claim 1, which is 6-naphthalate. 3. The laminated polyester film according to claim 2, wherein the polyester (B) is polyethylene terephthalate or poly-1,4-cyclohexylene dimethylene terephthalate. 4. The polyester (A) is polyethylene terephthalate, and the polyester (B) is poly-1,4-
The laminated polyester film according to claim 1, which is cyclohexylene dimethylene terephthalate.